I was looking for a cheap surround sound system that would support 5.1 dolby digital audio through a fibre optic connection, (for use with the xbox 360, so it needs to have a decoder) I use the same monitor for my xbox and pc with a vga switcher, so it must also be able to take 3x analogue coaxial mini jacks or 1x digital mini jack aswell (from a creative xfi) I have looked around and can't find any of the leading pc 5.1 speakers with optical connections on at all, so I would really appreciate any help.

The Logitech Z-5500 5.1 speaker system comes with an external decoder and has exactly the inputs that you are looking for. The 3 pc inputs, 1 digital coax and 1 optical input.

http://www.logitech.com/index.cfm/ [...] 4&cl=us,en

I actually have the exact same setup with my XBox and PC plugged into the same screen and I use the digital out on the XBox with the speakers.

You should also be able to pick them up for a really good price.

Go for the z-5500's I have the exact same setup, it has one digital coax and one optical input also. I'm using a xFi card with mine also.
I would really recommend it.

z-5400 and z-5300e also support coax and optical and are a damn sight cheaper

Is that what the port is on the back of the cable for the 360, an optical port?

z5300e doesnt support digital input, my bad